Extrusion press closure



' p 10, 1957 P. BILLEN 2,805,445

EXTRUSION PRESS CLOSURE Filed NOV. 8, 1954 PELLZeIZJ EXTRUSION PRESS cLosURE Peter Billen, Leverkusen-Kuppersteg, Germany, asslgnor to Schloemann Aktieugesellschaft, Dusseldorf, Germany Application November 8, 1954, Serial No. 467,552 Claims priority, application Germany January 17, 1953 5 Claims. (Cl. 18-12) Many extrusion presses, more particularly those suitable for the production of carbon electrodes, operate in such a manner that a certain quantity of the material to be pressed is fed into the receivers, where it is compressed by one forward motion of the press plunger, whereupon the press plunger moves backwards again. Thereupon a certain quantity of the material to be pressed is again introduced and the press plunger again advanced, so that this quantity as well will be compressed and so on, until the receiver is filled with compressed material. Among other reasons the material is compressed by stages, in order to give the air contained in it the possibility of escaping. In many cases it is also desirable to compress the charge with greater force than is required for the extrusion of the material. The latter is more particularly the case when the degree of deformation during extrusion is relatively small, that is, when the cross-section of the container outlet is large in relation to the diameter of the receiver.

In all those cases in which a compression of the charge is required, the receiver must be closed during the compression, in order to enable the desired pressure for the compression to be reached. It has already been proposed to close the receiver aperture by means of a hydraulically moved piston. In this case the closing member must be held by the hydraulically operated piston with such pressure against the aperture of the receiver that it will be capable of offering the necessary resistance to the material under pressure.

Now, the invention has for its object to carry out the closing of the receiver with only slight fluid pressure and consists in this, that a cylinder, in which a piston rigidly connected with the closure body can be subjected to hydraulic action, is in communication with its pressure medium supply pipe by way of a non-return valve which bars the outflow of the pressure fluid out of the cylinder. In this way it is possible to make do with a low tiuid pressure, for instance one of from 1 to 2 atmospheres.

For facilitating the opening of the receiver the nonreturn valve can be opened at will, for instance by means of a hand-operated spindle. For working with such a closure head it may be found to be of advantage for the closure body along with the piston to be displaceable by means of a hand-operated device in opposition to the fluid pressure, the hand-operated device being preferably positively connected with the closure body. In this way it is possible to open the receiver without the necessity of first relieving the fluid pressure acting on the piston.

The invention also concerns a particularly efiective construction of the closure arrangement, which enables it to be applied and removed in a simple manner.

The accompanying drawing illustrates a constructional example of the invention and shows the orifice of a receiver with a closure according to the invention.

A cylindrical receiver 1 has an orifice 2, out of which the material to be compressed is to be forced. For this purpose a plunger 3 moves in the receiver 1. At the end the receiver has abutments 5, whilst the cylinder body for its part is provided with abutments 6 which coact with the abutments 5 in the manner of a bayonent union.

The closure body 7 is rigidly connected with a piston 8 which is slidable in the cylindrical space 9 of the cylinder body 4. The cylindrical space 9 is in communication by way of a non-return valve 10 with the pressure medium supply pipe 11 which opens into the lower part of a pressure accumulator 12. The accumulator is filled to about one third with water, its upper part 12a being filled with air. For the occasional filling up of the accumulator 12 with compressed air a valve 13 is provided, to which a compressed air hose may be attached. The accumulator is of cylindrical form, so that it surrounds the cylinder body 4 on all sides. The non-return valve 1% has a stop member 14 which closes the valve when the pressure in the space 9 exceeds the pressure in the accumulator 12. The stop member 14 liberates the flow through the valve 11) in the direction towards the space 12, on being forced downwards by a hand-operated spindle 15. Through the piston 8 extends a rod 16 which with a collar 17 bears against the piston 8. The collar 17 has clearance in a recess 13 of the piston body 5. The spindle 16 is supported with a thread 19 in the cylinder body 4 and can be turned by means of a hand wheel 20.

When the filling material is to be precornpressed, the cylinder body 4 is mounted by means of the abutments 5 and 6 firmly on the receiver 1, the closure body 7 being drawn into the cylinder 9 by means of the spindle 16. When the cylinder body 4 has been fixed to the receiver 1, the spindle 16, with its thread 19 is turned inwards, until a clearance is established between the piston 8 and the abutment 1'7. Thereupon the piston 8 follows the abutment 7 of the spindle 16, since, owing to the expansion of the compressed air present in the upper part 12a of the accumulator 12, the pressure water enters into the cylinder space 9 through the pressure pipe 11 and acts on the piston 8. As soon as the closure plate 7 abuts against the receiver 1, the clearance between the abutment 17 and the piston 8 is produced. The filling of the receiver can then start, the plunger 3 being withdrawn and the material to be pressed being filled in. On the plunger 3 moving forward again, it will compress the material and among other things force it against the closure body 7, an abutment for the closure body being provided by the fiuid which is present in the cylinder 9 and is prevented from escaping by the non-return valve 111. The plunger 3 is thereupon withdrawn again, a fresh charge of material introduced and the plunger again driven forward. After this operation has been repeated a number of times, the receiver will be full.

For effecting the extrusion the closure arrangement must then be removed. For effecting this, the nonreturn valve 15 is opened by turning the spindle 15, so as to allow the pressure fluid in the space 9 which is under a much higher pressure than the accumulator 12 to escape through the pipe 11. By turning the spindle 16 by means of the hand-wheel 2d the piston 8 is then completely withdrawn into the cylinder space 9, overcoming the low pressure of the accumulator. At the same time the closure body 7 will detach itself from the pressed material, so that the entire closure can be released by turning the cylinder body 4. The pressed material is thereupon forced out.

I claim:

1. In an extrusion press, more particularly an extrusion press for the production of carbon electrodes, a receiver, a removable closure body capable of closing the opening at the output end of the receiver, and a device adapted to press the closure body against the output end of the receiver, the said device comprising: a cylinder co-axial with the receiver, means for temporarily securing the cylinder to the output end of the receiver, a piston slidable in the cylinder and rigidly connected with the closure body, a pressure accumulator, a ppe line connect: ing the pressure accumulator with the cylinder, -a non return valve normally preventing the refurn of fiu id fr om the cylinder to the pressure accumnlaton andmeans for manually opening the non-return valveat will to permit such return of fluid.

2. In an extrusion press, a device as-claimed in claim 1, further comprising manually operated means for retracting the piston and thereby Withdrawing the closure body from the opening at the output end of the receiver against the thrust caused by'the accumulator pressure.

3. In an extrusion press, a device as claimed in claim 2, whereinlthe retracting means include a screw-threaded spindle extending through the outer end of the cylinder and also'extend-ing through the piston, and means such as a hand-Wheel for manually rotating the spindle, the piston being formed with a central recess in its inner end face, and the spindle being 'formed with a head at its inner end engaging in the said recess.

4. In an extrusion press, a device as claimed in claim 2, wherein the pressure accumulator is a cylindrical container surrounding the cylinder, the device further comprising a valve through which air can be forced into the accumulator up to a gauge pressure of between one and two atmospheres.

5. In an extrusion press, a device as claimed in claim 1, wherein the means for temporarily securing the cylinder to the output end of the receiver include a bayonet joint.

References (Iited in the file of this patent UNITED STATES PATENTS 2,319,145 Loomis May 11, 1943 2,340,009 Meakin Jan. 25, 1944 2,617,169 Bodkin NOV. 11, 1952 FOREIGN PATENTS 427,571 Great Britain Apr. 26, '1935 478,862 Italy Mar. 5, 1953 

